Magnetron telegraphic repeater



Nov. 5, 1940. 4 M m 2,220,379

MAGNETRON 'IELECRAYHIC REPEATER Filed Dec. 20, 1937 LOUIS M. PoT'Ts AHUANEY.

'M-(I-l) Patented Nov. 5, i940 UNITED STATES MAGNETRON TELEGRAPHIC REPEATER Louis M. Potts, Evanston, IlL, assignor to Teletype Corporation, Chicago, 111., a. corporation of Delaware Application December 20,1937, Serial No. 180,717

12 Claims.

This invention pertains to telegraphic systems and apparatus and more particularly to such systems in which the distance between terminal stations renders necessary the provision of an intermediate station equipment with telegraphic repeating devices to renew the strength of the signal impulses.

The invention pertains more particularly to systems which serve a large traffic at a high speed of transmission in which the time required for the operation of mechanical armatures of magnetic relays becomes a restraining feature in the speed of operation of the system, particularly from the viewpoint of repeating the impulses at a repeater station where transit time of an armature in a mechanical electromagnetic relay introduces a degree of distortion into the time dimension of repeated impulses.

Accordingly, the present invention has as its principal object the provision of repeating equipment wholly independent of any mechanically movable elements.

Features of the invention are'embodied in an improved substation equipment and in details of elements of the assembled system and in variations of the preferred form of the invention.

The invention is illustrated in its preferred form; namely, an arrangement to provide circuits including a symmetrical assembly of elec- 3n tronic devices to effect two-way single-line transmission through a repeating station with suppression oi echo signals by means wholly independent of any mechanical operating member. Transmission also is effected through a repeating 3!; station by reversed signals or open-circuit principles, and signal impulses are reversed at a terminal station to operate a recorder of closed circuit type.

For illustration of the invention, the drawings show a magnetron, comprising a tubular anode surrounding an axial cathode and surrounded by helical windings. When the cathode is heated and potential is appliedirom cathode to anode without current in any winding, the electronic path from cathode to anode, called plate circuit, is in conducting condition. When a magnetic field oi sufliicent strength is produced by current in either polar sense inthe windings, the plate circuit 01' a magnetron becomes non-conducting. An eflective magnetic field may be produced by a controlling current through a single winding in a magnetron, or a biasing current in one winding may produce a magnetic field which, when increased by a small controlling current in as another winding, may render the plate circuit v rents in response to'signals received from each oi.

non-conducting, or alternatively a biasing current in one winding may render the plate circuit non-conducting by a strong magnetic field which, when decreased by a small opposing controlling current in another winding, may render 5 the plate circuit conducting.

In the systems of the present invention, a plurality of magnetrons are associated by circuits to form a single-line two-way repeating system, and magnetic fields are combined differentially 10 or cumulatively in the'several magnetrons to effect suppression of reflection signals.

A better understanding of the invention may be had from the following description taken in conjunction with the accompanying drawing 16 wherein,

Fig. 1 illustrates circuits and apparatus of a system including two substations and'a repeating station operating upon closed circuit principles of telegraph transmission with echo suppression according to this invention:

Fig. 2 illustrates a modification thereof operating upon open-circuit principles with arrangement for echo suppression;

Fig. 3 illustrates a modification oi the structure of Fig, 1; and,

Fig. 4 illustrates a substation equipment for open circuit working.

Referring to the drawing for a detailed description, Fig. 1 illustrates a two-way magnetron repeating system between two line sections, having four magnetron tubes in which one tube is used foricontrolling transmission currents and one tube is used for controlling echo suppression cur- 35 the two line sections. Tubes I, 2, 3, and l have line windings 5, 6, 1, and 8 and biasing windings 9, I0, ,I I, I2, respectively. Local currents in echo= suppression windings and I5 are controlled by plate circuit I8 0! tube 4, and currents in echo suppression windings I4 and I6 are controlled by plate circuit I! of tube 3. Currents in the line windings are supplied from batteries I9 and 20 through resistors 2I, 22 and plate circuits 23, 24, of tubes I and 2, thence flowing through windings 5, 6, I, 8 in that polar sense indicated by arrows, and thence over line sections 25, 26 and through transmitters and receivers (not shown) insubstations 21, 28, respectively, and to ground.

In transmitting tubes I and 2, the biasing currents in windings 9 and I0 oppose the line currents in magnetic effect, the diflerence or remaining magnetic field being too weak to render either tube non-conducting, but the biasing current bemg sufllcient to render either tube or 2 non- I5 conducting when unopposed by either line or local current.

In tube 4, biasing current in winding I2 is ineflective to render the tube non-conducting but the tube 4 is non-conducting when current also is flowing in winding 8 or in winding I8. Tube 3 operates similarly.

For purposes of description, it will be assumed that a start-stop printing telegraph unit is used, such as described in U. S. Patent 1,904,164 issued to Morton et al., but the repeater is equally well adapted to many other types oi. telegraph machines.

In operation, tubes I and 2 are conducting while tubes 8 and 4 are non-conducting, for a marking signal.

Upon operation of the transmitter (not shown) in substation 21 for a spacing signal, current is interrupted in line 28 and in line windings 8 and 1, permitting magnetron 8 to render its plate circuit I1 conducting, and causing magnetron I to render its plate circuit 23 non-conducting. The non-conducting condition of plate circuit 28 interrupts current in line 28 and in line windings 8 and 8, while the conducting condition of plate circuit I1 establishes current in local windings I4 and I6, replacing magnetic eiiects of current discontinued from line windings 8 and 8 and effecting echo suppression in both tubes 2 and 4.

Upon reclosing the line 25 at substation 21 to reestablish the original signaling condition of marking nature, current will flow from battery 28, through resistor 22 and. conducting plate circuit 24 of magnetron2, through line windings 5 and 1, line 25, and substation 21 to ground. Magnetrons I and 8 will return to conducting and non-conducting conditions respectively, current in windings I4 and I8 will be discontinued, and current in line 28 and line windings 8 and 8 will be restored.

A modification is illustrated in Fig. 2 in which but two magnetrons are used. Each magnetron 1|, 12 isprovided with a local winding 18, 14, a receiving line winding 15, 18', and a retransmitting line winding 11, 18. Eachreceiving circuit includes a thermo-electronic valve 18, 88. Two substations 8|, 82 are shown connected through line conductors 88, 84 to grids 85, 88, respectively, and branching through windings 11, 18, respectively, to plate circuits of magnetrons 12, 1|, respectively, and through resistors 88, 81 to battery connections. Local circuits for received signals include cathodes 88, 88, plates 8I, 82, windings 18, 18, portions of potentiometer resistors 88, 84, and contactors 85, 88. At substation 8|, the line conductor 88 is connected through a neutral relay I8I and a resistor I88 to a ground connection, to complete a line circuit for received signals, which is supplemented by a local circuit for received signals including a battery I88, recorder selector magnet I81, and a back contact and armature of deenergized line relay I8I. There is provided also a transmitting equipment including battery I88, a resistor III, a transmitting armature H8 and back contact, which has the function of applying the potential of battery I 88 to the line conductor 88 for signaling effeet in response to control by a permutation transmitter I88.

current from valves 18, 88 through windings 15,

18, when flowing in response to a received signal oi spacing nature, are opposed to the currents in magnetic eiiect and are suflicient in intensity to reduce the energization of the respective tubes to a degree permitting the plate circuits to become conducting when no current is flowing in winding 11 or 18, respectively. but insufiicent to render the plate circuits conducting against the joint magnetic effect of currents in windings 18, 11 or windings 14, 18. I

The structure of Fig. 2 is illustrated in condition of a continuous marking signal as indicated by the energized condition of the recording magnets I81, I88 at the substations 8|, 82, with the contacts of transmitter II8 open, with the marking condition of no current upon the line conductors '83, 84, no currents in'windings 18, 18, 11, 18, and with currents as described above in local windings 18, 14, rendering magnetrons 1| and 12 non-conducting.

'A spacing signal is effected in the system by renders the plate circuit of valve 18 conducting thereby establishing current in winding 15 and rendering the plate circuit of tube 1| conducting to establish current in winding 18 oftube 12 and relay I82 in substation 82, and also polarizing the grid 88 in valve 88. Current in winding 18 increases the magnetic iield in tube 12. Energization oi. relay I82 operates its armature and produces a repeated spacing signal in the remote recorder I88 and polarization of grid 88 renders the valve, 88 conducting and establishes a current in 'winding 18. Since the current in winding 18 was established before the opposing current in winding 18, the plate circuit of the magnetron 12 has been held non-conducting through the described operation.

To reestablish the marking condition in the system, contact of transmitter I88 is closed, reenergizing the relay II8, interrupting current in relay I8I, which reestablishes marking conditions in home recorder I81, and interrupting also polarization 01' grid 88 which interrupts current in winding 18 and restores the plate circuit oi magnetron 11 to non-conducting condition to interrupt current in line relay I82 which releases its armature and eii'ects a repeated marking signal in remote recorder I88. Magnetron 1|, in resuming its non-conducting plate circuit condition, depolarlzes the grid 88 and interrupts current in winding 18. Interruption of current in winding 18 leaves magnetron 12 to the combined influence oi currents in windings 14 and 18, which is a condition to render the plate circuit of the magnetron conducting but depolarization of the grid 88 at this time renders valve 88 non-conducting and immediately thereafter interrupts the current in winding 18 to restore magnetron 12 to its normal magnetic condition with a non-conducting plate circuit.

With reference to Fig. 3, twoline sections 81, 88 are shown connecting two substations 88, 88 to a central oillce, equipment wherein line section 81 is connected to magnetrons 42, 48 and line section 88 is connected to magnetrons 4|, 44. Biasing windings are indicated at 48, 88, 8|, 82. A line signaling circuit extends from grounded battery through resistor 54, plate circult of magnetron 42, winding 88 of magnetron 48, line section 81, and substation 58 to ground.

A companion line circuit extends from grounded.

; battery throughresistor 53, plate circuit of magnetron 4|, winding 56 of magnetron 44, line 58 and substation to ground. Local circuit un der control of signals in line circuit 51 extends from grounded battery through resistor 62, winding 64 of magnetron 44, winding 41 of magnetron 4| and plate circuit of magnetron 43 to ground, the winding 41 being shunted by a condenser 45. This circuit is open by virtue of non-conducting plate circuits in magnetron 43 when the signal in line section 51 is a marking signal.

With a marking signal in the two line sections 5.1, 58, the two magnetrons 4|, 42 are biased only by current in windings 49, 50, and their plate circuits are conducting while the two magnetrons 43, 44 each biased by magnetism of its biasing windings 5| or 52 and supplemented by magnetism of its line windings 55, 56, are both non-conducting.

Beginning of current in the described local circuithas first the effect of producing a magnetic field in magnetron 44, simultaneously charging the condenser 45, and subsequently producing a magnetic field in magnetron 4| after a delay due to the presence of condenser 45, which acts as a by-pass for the initial moment of current flow in the described local circuit.

In operation the beginning of a spacing signal at substation 59 will open the described line circuit, thus decreasing the magnetization of magnetron 43 and causing its plate circuit to become conducting, thus starting current in the described local circuit and increasing the magnetization of magnetron 44 to'continue the nonconducting condition of its plate circuit after which current in winding 4'! of the local circuit increases magnetization of magnetron 4| and renders its plate circuit non-conducting, thus opening the circuit of the line section 58 and repeating into substation 50 the spacing signal originated in substation 59. At the cessation of current in line section 58 no efi'ect is produced in magnetron 44 since the magnetism of winding 64 replaces the magnetism of winding 56 and jointly with the magnetism of biasing winding 52 maintains the magnetron 44 in non-conducting condition, thus estopping echo signals.

Upon reclosing the circuit of substation 59 to begin the ensuing marking signal, current flows again through winding 55 rendering the plate circuit of magnetron 43 non-conducting and preserving the plate circuit of magnetron 44 conducting, followed immediately by cessation of current in winding 41, thus rendering magnetron 4| conducting and restoring current in line section 58, repeating in substation 60 the marking signal generated in substation 59. Transmission in reverse order from substation 59 is obvious. Any current impulse in the local circuit from grounded battery through resistor 6|, winding 63, winding 48, and plate circuit of magnetron 44 which may occur during the period of discharge of condenser 45 is so brief that it is negligible and.

ineffective upon either substation 59 or 60.

A substation equipment is illustrated in Fig. 4 whereinis shown an assembly operating under the conditions explained above for substation 8|, Fig. 2. A thermo-electronic valve I20 has its grid I2I connected to line conductor I22 and its plate circuit connected through winding I23 of recorder magnet 'I24 which is electro-polarized by its winding I25 over an obvious circuit. A transmitter, when operated to open its contacts, deenergizes a relay whose contact I26, when re- I24 and contact I26 of the leased, connects battery I21 through resistor, I28 to lineconductor I22. The structure of Fig. 4 is illustrated inits normal condition of a marking signal as evidenced by the attracted positions of the armature I29 of recorder magnet transmitter relay. In this condition, the line conductor I22 is withoutpotential, the grid I2I is at ground potential, no current flows in winding I23, and polarizing current in winding I25 is .suflicient to cause the recorder magnet I24 to hold its armature I29 after return of thearmature I29 to-the pole of the magnet I24 by (not shown). Upon receipt of a signal of spacing nature upon grid I2I, either from the home transmitter contact I26 or over the line conductor I22, current will flow in the plate circuit of valve I20 and in winding I23, decreasing the electromagnetic field produced by uniform current in winding I25 and releasing the armature I29 to effect a signal of spacing nature in the recorder.

The magnet I24 is illustrated as a holding magin which patent will be found the details of operation of mechanically assisted armature I29. The invention has been described in connection with specific illustrative systems which are capable of modiflcationwithout departing from the spirit or scope of theinvention, the invention being limited only by the scope of the appended claims.

What is claimed is:

1. In a-telegraph two-way single-line repeating system, two line sections, each said section oper ating alternatively as a line circuit for received signals or as a line circuit for retransmitted signals, two pairs of signal responsive magnetron valves, one of said pairs having windings for incoming signals included in a circuit with one of said line sections, the space discharge gap of one valve of said one pair being included in a circuit with the other of said line sections for retransmechanical action of a cam mission signals, andthe space discharge gap of the other valve of said one pair being included in an echo-suppression circuit.

2. In a telegraph two-way single-line repeating system, two line sections, each said section operating alternatively as a line circuit for received signals or as a line circuit for retransmitted signals, two pairs of signal responsive magnetron valves, one pair having signal receiving windings included in a circuit with one of said line sections, 8. space discharge gap of one valve of said one pair being included in a retransmission circuit with the other of said line sections for generating retransmission signals in response to received signals, and the space discharge gap of the other valve of said one pair being included in a circuit including also windings of each of the valves of the other pair of said signal responsive magnetron valves whereby said other pair of mally closed space discharge gap, and echo-suppression means included in a normally currentless circuit with said normally open space dis-' charge gap, whereby upon receipt of a changed signal said normally currentless circuit will be closed by said normally open plate space gap and will be supplied with current for rendering said echo-suppression means effective.

4; In a telegraph two-way single-line repeating system, two associated magnetrons simultaneously responsive to received signals, a normally closed plate circuit in one of said magnetrons, a normally open plate circuit in the other of said magnetrons. a retransmission conductor included in circuit with said normally closed plate circuit, and echo-suppression means additional to said two magnetrons and included in said normally open plate circuit of said other of said two magnetrons.

5. In a telegraph two-way single-line repeating system, two associated magnetrons simultaneously responsive to received signals, a retransmission conductor included in the plate circuit of one of said magnetrons, and echo-suppression means additional to said two magnetrons and included in the plate circuit of the other of said magnetrons.

6. In a telegraph two-way single-line repeating system, two line sections, two associated magnetrons having respectively normally conducting and normally non-conducting space discharge paths and responsive to signals from one of said line sections, means controlled by one of said magnetrons to repeat the received signals over the other of said line sections, and means controlled by the other of said magnetrons to effect estoppel of reflection signals.

7. In a telegraph two-way single-line repeating system, two line sections, a quick-to-operate magnetron and a slow-to-operate magnetron both responsive to signals from one of said line sections. means controlled by said slow-to-operate magnetron to repeat the received signals over the other of said line sections, and means controlled by said quick-to-operate magnetron to effect estoppel of reflection signals.

8. In a telegraph two-way single-line repeating system, two line sections, two signal responsive magnetrons normally in space conducting condition controlled over said line sections respectively, two further signal responsive magnetrons normally in space non-conducting condition controlled over said line sectionsrespectively, and repeating circuits for said magnetrons each repeating circuit including a space path in one of said magnetrons, a winding in one of said further magnetrons and one of said line sections.

9. In a telegraph two-way, single channel repeating system, two line sections, two magnetrons responsive to signals received over said line sections respectively, polarizing windings in' said magnetrons, said windings being energized continuously and effective when unopposed to render said magnetrons nonconductive, and two line circuits normally carrying current, each circuit including one of said line sections, the plate circuit of one of said magnetrons and a winding of the other magnetron, said winding being effective when energized by the line current to oppose the polarizing winding and render said other magnetron conductive.

10. In a telegraph two-waysingle-channel repeating system, two line sections, two'signal repeating magnetrons connected in retransmitting manner by electromagnetic coupling between said two line sections, and means responsive directly to received signals to estop reflection signals.

11. In a telegraph two-way single-line repeating system, two line sections, two magnetrons having windings controlled by one ofsaid line sections and responsive to signalsreceived from said line section, 'a condenser connected as a shunt with one of said windings, one of said magnetrons being operative to repeat the received signals, and the other of said magnetrons being operative to effect estoppel of reflection signals. 1

12. In a telegraph two way single-line repeating system, two line section circuits, each circuit operating alternatively as a line circuit for received signals or as a line circuit for retransmitted signals, two space-discharge devices, one for each of said circuits, the space-discharge path of the device being included as a part of the circuit, first means for maintaining either of said spacedischarge paths in conductive condition in one of said circuits during periods of marking-signals in the other of said circuits, and second means for maintaining one only of said space-discharge paths in conductive condition in one of said circuits during periods of concurrent spacing signals in both of said circuits.

LOUIS M. PO'I'IS. 

